Analysis Automatic Steering Control System Each RAD unit has its own set of PCBs and transducers and one control head (joystick) controls two RADs. However, both electrically and mechanically, the two RADs are completely isolated from each other. The only common point is the control head itself and the main driving gears, cams and shafts within it. While the cause of the ferry moving away from the dock and then quickly back toward it again, was not determined, the automatic steering control system has been known to behave erratically on several occasions.3 Interviews with the crews of British Columbia Ferry Corporation (BC Ferries) vessels fitted with similar RADs and steering control systems, show that all nine vessels have a similar history. It appears that these RADs will, suddenly and without warning, spontaneously rotate independently of the command signal. Sometimes the RAD legs rotate through 360and stop of their own accord, although most times they continue turning until the engine is shut down. There have been numerous instances where one RAD leg has spontaneously rotated. While it is not unknown for two RADs to spontaneously rotate simultaneously, these instances are comparatively infrequent. The effect of such a rotation on a vessel under way, would be to move the vessel off course. For a vessel in dock, the effect would depend on the number of RAD legs that rotated. The rotation of one leg would just make the ferry move sideways - the net forward thrust would always be greater than that of the rotating leg and the ferry would continue to push against the dock. The effect of two legs rotating would be dynamic and would change with the changing angular difference between the forward and after pairs of legs. It would also be a function of the thrust being produced at each propeller shaft and of the ricocheting wash off the wing walls of the dock. Trials were later conducted on the BowenQueen when the vessel was lined up in dock and all four legs were pushing against it. Both the forward and after pairs of legs were separately rotated and on both occasions it was found that the vessel moved out of the dock. Rotation of the forward legs caused it to move straight out; while rotation of the after legs caused it to first move sideways and bear against the floating wing wall. Alarm System The alarm system warns of failures or malfunctions in the power supply and hydraulic circuits. However there is no audio-visual alarm to give warning of a spontaneous deviation between the command signal from the joystick (set point) and the actual position of the leg (measured value). A 'look out' on the bridge would become aware of such a rotation only by its effect on the ship's heading or by looking at the RAD angle indicator. Safety Management System An effective Safety Management System (SMS) should include procedures to ensure that accidents, non-conformities and 'near misses' are reported to the vessel's owners and operators and that these are investigated and analysed with the objective of improving safety. Further, procedures should be established for the implementation of the necessary corrective action. BC Ferries owns nine vessels fitted with RADs and similar automatic control systems, all made by the same manufacturer and all having a similar history of occasional erratic behaviour. The causes of such malfunctions vary and could be due to a variety of reasons; from disruptions in the feedback signal, improper shielding of the cables, defective transducers, faults in the hydraulic circuit, improper isolation and grounding while welding, to defective PCBs, etc. Interviews with BC Ferries personnel and with the manufacturers indicate that defective PCBs are the most frequent cause of RAD malfunction. According to the PCB manufacturers, the performance of the cards tends to deteriorate with time and it is recommended that they be renewed after they are about 10years old. While most of the PCBs are fifteen to twenty years old, some are newer and until very recently, they did not have an identification or serial number. There is thus no way of knowing the age, or history, of the majority of the cards. The SMS requires that there be a planned maintenance system and that malfunctions be analysed, with a view to optimising performance and eradicating failures. At the time of the investigation, neither BC Ferries nor the manufacturer of the PCBs had such a system in place, nor is there any kind of trend monitoring done on the failures. Defective cards, without identification as to the originating vessel, are often sent to the manufacturer indirectly via a central despatching and receiving facility. Quite frequently, a description of the defect that necessitated the card(s) replacement and subsequent repair is not provided. When a vessel's crew is unable to rectify a RAD malfunction, the manufacturer is called out to effect a repair. Rarely has a report on the work done been submitted to the engineering superintendent's office, or to the vessel's master or chief engineer. An efficient and effective SMS requires the proper documentation of repairs to all critical equipment and for such documentation to be readily available to the vessel's current and future crews. Spontaneous rotation of either the forward or after pair of right-angled drive (RAD) units caused the vessel to back off from the dock and return toward it. While the definite cause of the RAD malfunction was not determined, information points to the defective printed circuit boards in the automatic control systems.Findings as to Causes and Contributing Factors Spontaneous rotation of either the forward or after pair of right-angled drive (RAD) units caused the vessel to back off from the dock and return toward it. While the definite cause of the RAD malfunction was not determined, information points to the defective printed circuit boards in the automatic control systems. There is no audio-visual alarm provided to give timely warning of a spontaneous deviation between the command signal from the joystick (set point) and the actual position of the RAD leg (measured value). Nine British Columbia Ferry Corporation (BCFerries) vessels are fitted with RADs and similar automatic control systems made by the same manufacturer and all of these vessels' RADs have a similar history of occasional erratic behaviour. At the time of the occurrence, BCFerries vessels' Safety Management Systems did not require that printed circuit boards were individually identified by serial numbers or that repairs to them were documented. At the time of the occurrence, neither BCFerries nor the manufacturers of the automatic control systems had a planned maintenance system to replace the printed circuit boards.Findings as to Risks There is no audio-visual alarm provided to give timely warning of a spontaneous deviation between the command signal from the joystick (set point) and the actual position of the RAD leg (measured value). Nine British Columbia Ferry Corporation (BCFerries) vessels are fitted with RADs and similar automatic control systems made by the same manufacturer and all of these vessels' RADs have a similar history of occasional erratic behaviour. At the time of the occurrence, BCFerries vessels' Safety Management Systems did not require that printed circuit boards were individually identified by serial numbers or that repairs to them were documented. At the time of the occurrence, neither BCFerries nor the manufacturers of the automatic control systems had a planned maintenance system to replace the printed circuit boards. Safety Action Action Taken Repairs to the control system of the BowenQueen were completed during a drydock and refit in September 2002. British Columbia Ferry Corporation (BC Ferries) and the manufacturers of the automatic steering control system are in the process of drawing up a comprehensive 'time based' planned maintenance schedule for the PCBs. Components which deteriorate with time have been identified and these will be replaced when they reach the end of their working life. (seeAppendixA) It is planned to have the system in place on the BowenQueen and on the other eight vessels that share system components by July 2003. A 'repair log' is being maintained by the manufacturers of the automatic steering control system. PCBs are assigned identification numbers and a record of the defects found and repairs carried out is maintained. Copies are also kept on board the vessels and in the office of BC Ferries' Engineering Superintendent. All future defects and problems with the steering control systems on the nine vessels will be documented and tracked. To ensure the integrity of the automatic steering controls, a thorough inspection of the entire system and all its components on all nine vessels was done by the manufacturers of the automatic steering control system. In addition, BC Ferries management has retained the services of independent engineering consultants to do a separate review. Their mandate is to establish whether systems problems exist, and whether there are other actions which could improve safety.